Directional differential pressure detector having a differential pressure set point indicator

ABSTRACT

Methods and apparatuses for indicating the presence of a threshold directional differential pressure between separated adjacent spaces. A conduit contains at least one movable element that indicates whether the pressure difference between the two spaces is at least as high as a threshold pressure difference. The apparatus is adjustable to have different threshold set points by adjusting the pivot arm inclination relative to a horizontal plane.

FIELD

Disclosed embodiments relate to methods and apparatuses for detectingthe presence of a directional differential pressure.

BACKGROUND

Various applications within hospitals, laboratories, pharmaceuticalfacilities, clean room facilities, etc., often require a particulardirection of air flow or differential pressure to be maintained, such asbetween neighboring rooms, compartments, corridors, ducts, or otherspaces. The pressure of a room relative to adjacent space(s) willdetermine the net direction of air flow through an opening into or outof the room.

For example, a hospital operating room may be kept under a positivepressure so that air flows out of the room, thereby preventingunfiltered or contaminated air from entering the room from adjacentspaces. This positive pressure is accomplished by supplying clean air tothe operating room at a greater flow rate than the flow rate at whichair is exhausted from the room by the room's ventilation system.

Or, if a hospital patient is infected with an airborne communicablepathogen, a patient isolation room may be kept under a negative pressurewhich is accomplished when the rate at which potentially contaminatedair is exhausted from the room is greater than the rate at which air issupplied to the room from the room's ventilation system. Such a negativepressure arrangement, where the room is under a comparatively lowerpressure than its immediate surroundings, prevents potentiallycontaminated air from exiting the room and escaping into surroundingspace(s).

The net differential pressure between rooms will cause air to flowthrough an opening from one room to the other in the direction from ahigher pressure to a lower pressure. The desired degree of differentialpressure to be maintained between rooms, compartments, corridors, etc.will vary, depending on the application.

Accordingly, it is often desirable to closely monitor the generaldirection of potential or actual air flow between compartments and insome cases the particular magnitude of differential pressure causing thenet air flow.

SUMMARY

In some embodiments, a device for indicating a presence of a directionaldifferential pressure between a first space and a second space separatedfrom the first space by a barrier includes a rotatable base configuredto be rotatably attached to the barrier, and a first conduit coupled tothe base, where when the rotatable base is rotated, an inclination ofthe first conduit is adjusted relative to a horizontal plane. The devicealso includes at least one movable element disposed within the firstconduit and movable from a first, vertically lower region of the firstconduit to a second, vertically higher region of the first conduit inresponse to the directional differential pressure between the first andsecond spaces being greater than a threshold differential pressure, anda differential pressure set point indicator fixed to the rotatable base,where the differential pressure set point indicator includes a vialshaped in an arc and at least one movable marker disposed in the vial.

In some embodiments, a device for indicating a presence of a directionaldifferential pressure between a first space and a second space separatedfrom the first space by a barrier includes a rotatable base configuredto be rotatably attached to the barrier, and a first conduit coupled tothe base, where when the rotatable base is rotated, an inclination ofthe first conduit is adjusted relative to a horizontal plane. The devicealso includes at least one movable element disposed within the firstconduit and movable from a first, vertically lower region of the firstconduit to a second, vertically higher region of the first conduit inresponse to the directional differential pressure between the first andsecond spaces being greater than a threshold differential pressure, anda wall plate configured to rotatably secure the rotatable base to thebarrier. The wall plate includes a first level configured to indicatewhether an axis of rotation of the first conduit is aligned with thehorizontal plane, and a second level configured to indicate whether thewall plate is in a correct roll orientation relative to the axis ofrotation of the first conduit.

Advantages, novel features, and objects of the present disclosure willbecome apparent from the following detailed description of the presentdisclosure when considered in conjunction with the accompanyingdrawings, which are schematic and which are not intended to be drawn toscale. For purposes of clarity, not every component is labeled in everyfigure, nor is every component of each embodiment of the presentdisclosure shown where illustration is not necessary to allow those ofordinary skill in the art to understand the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Variousembodiments of the present disclosure will now be described, by way ofexample, with reference to the accompanying drawings. The embodimentsand drawings shown are not intended to narrowly define the presentdisclosure. In the drawings:

FIG. 1 is a side schematic of one embodiment of a device for indicatinga directional differential pressure;

FIG. 2 is a front schematic of the device of FIG. 1;

FIG. 3 is a cross-sectional side schematic of the device of FIG. 1;

FIG. 4 is a front schematic of another embodiment of a device forindicating a directional differential pressure;

FIG. 5 is a front schematic of another embodiment of a device forindicating a directional differential pressure;

FIG. 6 is a partial cross-sectional view of one embodiment of adifferential pressure set point indicator;

FIG. 7 is a partial cross-sectional view of another embodiment of adifferential pressure set point indicator;

FIG. 8 is a partial cross-sectional view of another embodiment of adifferential pressure set point indicator;

FIG. 9 is a partial cross-sectional view of another embodiment of adifferential pressure set point indicator;

FIG. 10 is a partial cross-sectional view of another embodiment of adifferential pressure set point indicator;

FIG. 11 is a front schematic of another embodiment of a device forindicating a directional differential pressure;

FIG. 12 is a front view of another embodiment of a differential pressureset point indicator;

FIG. 13 is a side view of the differential pressure set point indicatorof FIG. 12;

FIG. 14 is a side view of another embodiment of a differential pressureset point indicator;

FIG. 15 is a front view of the differential pressure set point indicatorof FIG. 12 in a first position;

FIG. 16 is a front view of the differential pressure set point indicatorof FIG. 12 in a second position;

FIG. 17 is a side cross-sectional schematic of another embodiment of adevice for indicating a directional differential pressure;

FIG. 18 is a front schematic of the device of FIG. 17;

FIG. 19 is a perspective view of another embodiment of a device forindicating a directional differential pressure in a first position;

FIG. 20 is a perspective view of the device of FIG. 19 in a secondposition;

FIG. 21 is a perspective view of the device of FIG. 19 in a thirdposition;

FIG. 22 is an exploded view of the device of FIG. 19; and

FIG. 23 is a cross-sectional view of the device of FIG. 19.

DETAILED DESCRIPTION

The present disclosure relates to devices and systems which provide anindication of potential or actual directional air flow and/or whether aparticular degree of directional differential pressure exists betweenspaces (e.g., two neighboring rooms or a room and an adjacent corridor)separated by a barrier such as a wall. In some embodiments, the deviceincludes a first component located on a first side of a barrier, and asecond component located on a second side of the barrier such that eachcomponent is subject to the air pressure within its respective space.The overall device is adapted to react to pressure differences betweenthe two spaces to provide an indication to a viewer of the device. Insome embodiments, the device may include sensors which communicate astatus to a remote device.

An air flow conduit may extend from one space to another space (e.g.,room to hallway). According to some embodiments, a visual indicator suchas a lightweight ball or other movable element moves within the conduitin response to differences in air pressures between the two spaces. Forexample, in some embodiments, the air pressure in a room may be higherthan in an adjacent hallway, and if the difference surpasses a thresholdpressure, the movable element may move toward an end of the conduit toindicate the pressure difference exceeding the threshold.

An air flow conduit does not necessarily require that the conduit bearranged to permit air to be transferred from one space to another.Instead, the pressures on opposite sides of a wall may communicatewithout air flow moving all the way through the air flow conduit. Forexample, a conduit may pass from a hallway to a room, and a piston maybe positioned with within the conduit. If pressure in the room issufficiently higher than in the hallway to surpass a threshold pressuredifferential, the piston may move toward the hallway and be visiblewithin the conduit in the hallway. If the piston is sealed within theinterior of the conduit, no room air escapes into the hallway space,though a small amount of air flows behind the piston within the conduit.In this manner, the air flow conduit may provide a fluidic connectionbetween two spaces where some minor air flow occurs within the conduit,yet no air is transmitted from one space to the other.

As discussed further below, in other embodiments, the fluidic connectionmay allow air to be transmitted between two spaces until a ball seatsagainst an end of a conduit. In still further embodiments, air flow fromone space to another even when a ball (or other movable element) reachesthe end of its travel path.

In some embodiments, a device for indicating a differential pressurebetween two spaces includes a one or more conduits in communication withthe air in both spaces such that a movable element disposed in theconduit(s) can react to directional air flow caused by the differentialpressure. As described further herein, the conduit(s) may extend throughthe wall, and adjustability of the incline of portions of the device mayreside on both sides or a single side of the wall. The movable element(e.g., at least one ball) is disposed within a passageway of the conduitand moves freely back and forth along at least a portion of the lengthof the conduit. Restraints or end stops may be located at the ends or atother areas of the conduit to contain the ball within the conduit. Theend stops may have openings that allow fluid (e.g., air, gas, liquid,water vapor, etc.) to flow through the passageway of the conduit fromone end to an opposite end.

Systems are available for detecting whether a differential pressurebetween two spaces (e.g., between a clean room and an adjacent corridor)is above a threshold pressure difference. In some conventional systems,an inclined single conduit passes from one space to another through awall, and a movable ball is placed in the conduit. On one side of thewall, for example the clean room side, the conduit has a lower regionnear the wall inside of the clean room and a higher region away from thewall in the corridor. Gravity pulls the ball toward the lower region ofthe conduit near the wall. As the pressure in the clean room is raisedhigher than the corridor pressure, air pressure and/or air flow applyforces against the ball. Once the pressure difference between the cleanroom and the corridor reaches a threshold level, the force of the airagainst the ball overcomes the force of gravity, and the ball moves to ahigher region of the conduit. By observing the presence of the ball inthe higher region, a user can quickly see that the pressure differencebetween the two spaces equals or exceeds the desired directionaldifferential pressure threshold level. To change the threshold pressuredifference set point, the angle of inclination of the conduit isadjusted such that the amount of gravitational force on the ball in thedirection of the conduit is adjusted. That is, in some embodiments, agreater incline of the conduit in which the ball travels requires agreater pressure differential between the two rooms to overcome gravityand move the ball from a lower to a higher region.

Applicant has appreciated that it would be beneficial to provide adifferential pressure monitoring system where the threshold value ofdirectional differential pressure detection is adjustable from one sideof the wall (or other barrier) and/or the system can account for thewall being out of plumb. In some embodiments, a monitoring systemincludes a pivot arm (or multiple pivot arms) on one side of the wall,and the pivot arm includes a set point indicator that reacts to an angleof inclination using gravity instead of a measured reference to anotherphysical structure. The pivot arm may include a conduit which contains amovable element. In some embodiments, the arrangement of the pivot armrelative to the system permits pivoting of the pivot arm within avertical plane.

By providing independent adjustment of the inclination of a conduit onone side of the wall, adjustments to the threshold directionaldifferential pressure level can be made without having to access thedevice on both sides of the wall. Such an arrangement can be especiallyhelpful when various protocols must be followed to enter a room beingmonitored.

The walls or other barriers on which the monitoring devices disclosedherein are being installed may be out of plumb, that is, not strictlyvertical. Applicant has recognized that in such circumstances, pivotarms with angle indicators and/or threshold pressure level indicatorsmay provide inaccurate information if the indicators are based on anassumption that the wall is plumb. Embodiments disclosed herein providearrangements where accurate threshold directional differential pressureadjustment can be achieved even when the device is installed on anout-of-plumb wall. For example, in some embodiments, a conduit with themovable element therein is adjustable from one side of the wall, theconduit is pivotable within a vertical plane, and a set point indicatoris tied to gravity rather than being based on markings on portions ofthe device that are static relative to the wall. A device that links athreshold set point(s) to marking(s) on the wall and/or marking(s) onportions of the device that do not move relative to the wall and ofwhich set points were calibrated to a plumb wall, may cause errors whenmounted to an out-of-plumb wall. Additionally, if a conduit does notpivot in a single plane, improper initial mounting of the device to awall may cause inclination measurement errors, thereby causinginaccurate directional differential pressure measurement errors.

In some embodiments, one or more levels, such as bubble levels, may beused to confirm proper device installation and/or to provide anindication as to set points that are based on gravity/verticalinclination of a conduit relative to the horizontal plane. In someembodiments, the bubble level, or other measurement device, is used as adirectional differential pressure set point indicator.

Certain embodiments disclosed herein provide a large range of availableinclination angles. By providing a large angle range, a large range ofthreshold differential pressure set points are available. In someembodiments, the device is also arranged to permit pivoting such thatthe conduit containing the movable element (e.g., a ball), can be placedin different orientations relative to its associated wall (or otherbarrier), in some cases while maintaining its same inclination relativeto a horizontal plane. In some embodiments, the conduit that isperpendicular to an axis of rotation may be rotated a full 360° aboutthe axis of rotation. According to exemplary embodiments describedherein, a conduit including a movable element such as a lightweight ballmay be moved to an incline relative to a horizontal plane of greaterthan 10°, 20°, 30°, 45°, 60°, 75°, and 80° up to an incline of 90°. Theincline may be positive or negative relative to the horizontal plane.

As mentioned above, various embodiments disclosed herein may include adirectional differential pressure set point indicator associated withthe conduit that contains the movable element. The set point indicatormay be configured to correlate the incline of the conduit (with respectto the earth's gravitational pull) to a respective threshold directionaldifferential pressure between the two adjacent spaces—the thresholddirectional pressure difference being the difference which is sufficientto cause the movable element to move from a lower region of the inclinedconduit to a higher region. The directional differential pressure setpoint indicator may include, for example, a bubble vial, a rotatingweighted pendulum pointer, or any other suitable component that respondsto the incline of the conduit. The differential pressure set pointindicator may be appropriately calibrated such that the markings on thedirectional differential pressure set point indicator correspond tothreshold directional pressure differences that may exist between spacesseparated by a wall or other barrier. Accordingly, the directionaldifferential pressure set point indicator may provide an indication ofwhat angle of conduit inclination corresponds to the directionalthreshold differential pressure set point between the two separatedspaces.

In some embodiments, when installed, a conduit extends from one side ofa barrier (e.g., a wall) to the other side such that opposite ends ofthe conduit extend outwardly into neighboring spaces that are separatedby the wall. In some embodiments, only one end of the conduit extendsoutwardly from the wall. Fluid (such as air) is permitted to flowbetween the spaces through the conduit in some embodiments.

The pressure difference required to move the ball from a home position(the ball's position when there is no pressure difference between therooms) can vary based at least on the physical features of the conduit(e.g., passageway diameter, straightness/curvature, surface finish),physical features of the ball (e.g., diameter, weight, surface finish),degree of incline of the conduit, fluid properties of the media betweencompartments, and the orifice sizes at the end stops. In many cases,each of the above parameters is known to a sufficient degree such thatthreshold directional pressure differences can be linked to the angle ofinclination. In some embodiments, balls of different weights may be usedto adjust the threshold pressure differences. In such embodiments, theconduit angle may or may not be adjustable.

As an example, for a hospital isolation room occupied by a patient withan infectious disease that is capable of airborne transmission, it maybe desirable to keep the room at a negative differential pressurerelative to one or more adjacent rooms, so as to substantially preventairborne transmission of the disease to an adjacent room. In such anarrangement, the room's ventilation system exhausts more air than issupplied within it to an extent that the negative pressure is of agreater magnitude than any adjacent space. Thus, the conduit may beinstalled such that the end of the conduit that extends toward theisolation room (e.g., extends inside the isolation room) is at a higherposition than the opposite end of the conduit that extends toward aspace immediately exterior to the isolation room (e.g., into a corridor,a compartment, duct, or another room).

When the net directional differential pressure between the isolationroom and the outside space is zero (e.g., a door between the room andthe outside space is opened), or the pressure in the isolation room isgreater than the adjacent spaces, the ball will fall to the lower end ofthe conduit such that an observer inside the isolation room would not beable to view the ball; and where the opposite end of the conduit islocated within the neighboring room, it follows that an observer outsidethe isolation room in the neighboring room would be able to see theball. Or, if the conduit is substantially located within the isolationroom (e.g., in a pivot arm or turret-type configuration), the ball mayfall to the lower end of the conduit yet remain within the isolationroom (e.g., exposed or covered from view), or within the wall cavitybetween rooms. When the appropriate degree of negative pressure isapplied to the room, the ball moves upwardly within the conduit to thevertically higher end. That is, the difference between the pressure ofthe isolation room and the pressure in the outside space on the oppositeside of the wall causes forces on the ball that are sufficient to movethe ball upwardly where it can be conspicuously viewed from inside theisolation room—thereby indicating that at least the appropriatedirection of air flow through an opening between the rooms and degree ofnegative pressure is applied to the isolation room. It should be notedthat Applicant has appreciated that the communicating conduit can notonly be through one wall or barrier and sense the pressure conditions oneach side, but, in some embodiments, the conduit may leave a room andpass through adjacent spaces and open up to a space not immediatelyadjacent to the initial room.

In the case of a hospital operating room that is required to exhibit apositive pressure, so as to substantially prevent potentiallycontaminated air from flowing into the room from a surrounding space,the conduit may be installed such that the end of the conduit thatextends toward the operating room (e.g., extends inside the operatingroom) is at a lower position than the opposite end of the conduit thatextends toward the surrounding space exterior to the room. Thus, when asuitable amount of positive pressure is applied to the operating room,there is sufficient directional differential pressure to move the ballupwardly within the conduit to the conduit end toward the surroundingspace.

When installed, the conduit may be set at an appropriate angle ofinclination that corresponds to the desired threshold differentialpressure set point. In some embodiments, the desired differentialpressure set point may be between 0.001 inch of H₂O and 10 inches of H₂O(e.g., between 0.001 inch of H₂O and 1 inch of H₂O, between 0.001 inchof H₂O and 5 inch of H₂O, between 0.005 inches of H₂O and 0.5 inches ofH₂O, between 0.1 inch of H₂O and 0.5 inches of H₂O, between 0.01 inch ofH₂O and 0.1 inches of H₂O, between 0.01 inch of H₂O and 0.05 inches ofH₂O, between 0.01 inch of H₂O and 0.03 inches of H₂O, between 0.005inches of H₂O and 0.1 inch of H₂O, between 0.001 inch of H₂O and 0.005inches of H₂O, between 0.001 inch of H₂O and 0.003 inches of H₂O, etc.),as measured by a standard water column manometer. It will be appreciatedthat devices of the present disclosure may provide an indication ofother differential pressures between adjacent spaces outside of theseranges.

As discussed above, a differential pressure set point indicator may besecured to the conduit so as to provide a correlation between the angleof inclination of the conduit, the physical dimensions andconfigurations of the components of the system, and the thresholddifferential pressure between the spaces.

As an example, if the desired differential pressure threshold set pointis 0.02 inches of H₂O, then, given the components of the system (e.g.,ball, conduit, orifices), the conduit may be angled in such a mannerwhere the lower end of the conduit is toward the higher pressurecompartment and the higher end of the conduit is toward the lowerpressure compartment, that the force of gravity on the ball will beovercome by the pressure and any air flow forces on the ball in thedirection opposite gravity from the low to the high end of the conduit,created by at least 0.02 inches of H₂O pressure difference between thecompartments.

Applicant has recognized that the external calibration methods used toestablish an accurate relationship between the angle of tilt (i.e.,inclination) of the conduit and the threshold differential pressure canbe time-consuming and expensive. For example, once the device isinstalled, such external calibration methods may include the use of amanometer to measure the pressure differential between the adjacentspaces to which the device/conduit is coupled, and noting the angle oftilt of the conduit at which the ball moves from one end to an oppositeend (e.g., falling from the higher end to the lower end, or moving fromthe lower end to the higher end). To continue the calibration process,the pressure difference between the adjacent spaces is adjusted andmeasured, and the corresponding angle of tilt of the conduit at whichthe ball moves from one end to the other is further noted. These stepsof calibration are repeated for multiple pressure differentials andcorresponding angles of tilt for the device. As mentioned above, suchsteps of pressure measurement and calibration may be expensive andtime-consuming.

One possible method to avoid re-calibrating a device each time it isinstalled to a wall involves including markings on the device thatcorrelate the conduit's angle of inclination directly to thedifferential pressure between spaces that causes the ball to move fromone end to the other. Applicant has recognized that such a method mayrely on the orientation of the wall to which the device is mounted orresides against, which might not be aligned with the direction ofgravity (i.e., the wall might not be plumb). That is, providing markingsthat indicate particular threshold differential pressure values thereonmay lead to inaccurate results unless the wall is vertically alignedwith the direction of gravity (i.e., the wall is plumb) and theindicator is properly installed to the wall.

Applicant has appreciated that it may be advantageous to employ anindicator that is directly calibrated to gravity. For example, aninclinometer that responds to the force of gravity (e.g., bubbleinclinometer, pendulum inclinometer, etc.) may be mounted to anappropriate portion of the differential pressure detection device sothat an accurate determination can be made as to the actual degree oftilt of the conduit required to reach an equilibrium between the forceof gravity and the forces on the ball, arising from directionaldifferential pressure across the ball resulting from the directionaldifferential pressure between the adjacent spaces. Accordingly, theaccuracy of such a device is not reliant on whether the wall to which itis mounted or otherwise resides against is aligned with the direction ofgravity (i.e., plumb).

Further, Applicant has recognized that it may be advantageous to be ableto adjust the angle of inclination of the conduit containing the ballfrom only one side of the wall while maintaining the conduit in a singleplane, for example, a vertical plane. When pivoting the conduit in onlya vertical plane, various inclinometers, such as a weighted ball, or aweighted pendulum, that are positioned at a given roll orientationrelative to a longitudinal axis of the conduit (e.g. on the top of theconduit) will remain positioned at the same roll orientation relative tothe conduit throughout pivoting of the conduit. In a device whereadjusting the vertical inclination results in a lateral inclination aswell, the weighted pendulum may have a roll component when the conduitis moved, which may re-orient the bubble vial to an orientation thatmakes reading difficult, or in some cases, prevents proper measurement.For example, if a conduit rotates only within a conical space (ratherthan a planar space), any change in vertical inclination results in arolling of the conduit about its own axis, which would change the rolland yaw orientation of the inclinometer, such as the weighted pendulum.As with some embodiments disclosed herein, when pivoting in a verticalplane is possible without requiring other reorientation, the weightedpendulum would only change its pitch orientation.

In further embodiments of the present disclosure, a device for detectingwhether a threshold directional differential pressure is present betweentwo spaces separated by a wall may include multiple conduits thatprovide a continuous passageway through which air may flow betweenspaces on opposing sides of the wall. In some cases, such arrangementsmay allow for the angle of incline of the conduit that contains themovable element to be adjusted from one side of the wall, rather thanhaving to make adjustments to the angle of the incline of the conduitwhile coordinating adjustments from both sides of the wall. Such anarrangement is particularly useful for monitoring the differentialpressure between two rooms that have one or more rooms/spaces betweenthem which the conduit traverses.

For example, a conduit having at least one movable element (e.g.,lightweight ball) located therein may be arranged to extend along, beparallel to, or be rigidly coupled to an axis that rotates about a pivotpoint, where rotation of the conduit about the pivot point is accessiblefrom one side of the wall. In some embodiments, the pivot point ispositioned on one side of the wall, or is offset a suitable distancefrom one side of the wall. For example, the pivot point may be locatedwithin a space outside of the wall (e.g., spaced away from an exteriorsurface of the wall) or within a space between exterior surfaces of thewall. In some embodiments, the conduit may rotate without a set pivotpoint. For example, the conduit may be configured to translate androtate at the same time.

In some embodiments, a device for indicating a threshold directionaldifferential pressure may include a first pivot arm or rotatable basecoupled to a barrier which rotates about a first axis transverse to thebarrier. The device may also include a second pivot arm rotatablycoupled to the first pivot arm or rotatable base and configured torotate about a second axis transverse to the first axis. In someembodiments, the first axis may be perpendicular to the wall and thesecond axis may be perpendicular to the first axis. According to thisembodiments, rotatable base may be rotatable 360° about the first axis,and the pivot arm may be rotatable at least 180° about the second axis.Accordingly, such an arrangement may allow the pivot arm to be inclinedat any angle within a semi-spherical range of motion. The rotatable baseand pivot arm arrangement may also reduce the amount of space occupiedby the device while allowing the device to be adjusted to compensate forout of plumb barriers (e.g., non-vertical walls) so that an accuratethreshold differential pressure indication is produced by the device.

It should be noted that an axis or direction which is transverse toanother axis or direction does not need to intersect the axis to whichit is transverse in three-dimensional space. That is, any non-parallelaxes are transverse to one another even if they do not intersect inthree-dimensional space. Of course, transverse axes will intersect whenprojected onto a two-dimensional plane.

Turning to the figures, specific non-limiting embodiments are describedin further detail. It should be understood that the various systems,components, features, and methods described relative to theseembodiments may be used either individually and/or in any desiredcombination as the disclosure is not limited to only the specificembodiments described herein.

FIG. 1 is a side schematic view of one embodiment of a device 100 forindicating a threshold directional differential pressure. The embodimentof FIG. 1 includes a pivot arm 110 rotatable about an axis transverse toa barrier 10, 12 to adjust an angle of inclination of a conduit formedin the pivot arm. As shown in FIG. 1, the device includes a base plate102 which is secured to a first side 10 of a barrier defining a firstspace. The base plate includes a receptacle 104 configured to receive aflanged end 112 of the pivot arm. The flanges engage the receptacle torotatably secure the pivot arm to the base plate. The base plate alsoincludes circular grooves 106 which receive guides 114 of the pivot arm,to further constrain the pivot arm movement to rotation about a singleaxis. As shown in FIG. 1, the pivot arm includes a 90° bend, so that aninclination of an end of the pivot arm may be adjusted via rotation ofthe pivot arm about its axis. The base plate fluidly connects the pivotarm to a wall conduit 108 which connects to a second space defined by asecond side 12 of the barrier. Accordingly, the first space and secondspace are connected via wall conduit 108 and pivot arm 110.

According to the embodiment of FIG. 1, the pivot arm 110 includes afirst conduit through which air may pass as a result of a directionaldifferential pressure between the first space and the second space onopposite sides of the barrier 10, 12. The first conduit is configured tocontain a movable element such as a lightweight ball which moves basedon the angle of inclination of the pivot arm and the differentialpressure between the two spaces. As shown in FIG. 1, the pivot armincludes a window 116 which allows the movable element to be seen insideof the pivot arm when the movable element is aligned with the window.The pivot arm also includes an end stop 118 which is configured toretain the movable element inside of the pivot arm.

As shown in FIG. 1, the device includes a first level 120 and a secondlevel 122 which are disposed on the base plate 102 and are used toassist in mounting the rotatable base to the first side 10 of thebarrier to ensure the axis of rotation of the pivot arm extends in anappropriate direction. The first level 120 is arranged in a directiontransverse to the first side 10 of the barrier and is configured toindicate when the axis of the rotation of the pivot arm is aligned witha horizontal plane. The first level also indicates whether the baseplate 102 is aligned with a vertical plane. When the base plate issecured to the barrier, the first level also may indicate whether thebarrier is out of plumb and not vertical. As discussed above, if theaxis of rotation of the pivot arm is not aligned with a directionassumed during manufacturing, the threshold pressure to move a movableelement may be altered. Accordingly, an installer may verify that theassumptions regarding threshold pressure are applicable by ensuring thefirst level 120 indicates alignment of the axis of rotation of the pivotarm with a horizontal plane. For example, if the wall is not plumb, thebase plate 102 may be shimmed or otherwise adjusted until the firstlevel 120 shows that the device is level. In one embodiment, the firstlevel 120 may use an air bubble in liquid to indicate whether the deviceis oriented correctly. The second level 122 is configured to indicatevertical orientation of the base plate 102 on the barrier and istherefore oriented perpendicularly to the first level 120. That is, thesecond level indicates when the base plate is in a correct rollorientation relative to the axis of rotation of the pivot arm. Such anarrangement may be beneficial when the base plate includes markingswhich may indicate the value of a differential pressure or otherwiseprovide information to a user of the device.

As shown in FIG. 1, the device 100 also includes a transparent shield130 which may be used to protect the pivot arm from unintentionalcontact while allowing the pivot arm to remain visible so that adifferential pressure may be indicated. The shield includes an orifice132 which allows air to pass from the first side 10 of the barrier tothe pivot arm through end stop 118. Accordingly, the shield does notinterfere with the differential pressure based movement of a movableelement in the pivot arm. It should be noted that the shield may beomitted from the device 100 without a corresponding loss infunctionality of the pivot arm and/or movable element disposed therein.

FIG. 2 depicts the device 100 from a front view, with the view alignedwith an axis of rotation of the pivot arm 110. As noted previously, thepivot arm 110 is configured to rotate about an axis transverse (e.g.,perpendicular) to a barrier. The pivot arm includes a 90° bend whichallows the inclination of the end of the pivot arm to be adjustedrelative to a horizontal plane. As shown in FIG. 2, the pivot arm isrotated so that pivot arm end is inclined at a negative angle relativeto a horizontal plane. Such an arrangement may be beneficial in a spacewhich is to have a positive pressure. A ball (e.g., a movable element)200 is disposed in the pivot arm and is visible through the window 116.End stop 118 retains the ball inside the pivot arm. According to thedepicted embodiment, the end stop 118 includes an orifice 119 which issized and shaped to receive an end of the ball 200. The position of theball against the end stop and orifice may form a fluid (i.e., air)barrier between first and second spaces, which may be desirable toinhibit air transfer between spaces. As shown in FIG. 2, the pivot armalso includes internal stops 124. The internal stops are configured tokeep the ball 200 within the pivot arm, particularly in the end of thepivot arm where inclination may be adjusted. The internal stops arepositioned so that when a differential pressure or gravity moves theball 200 into the opaque portion of the conduit, the ball is stopped ina portion of the conduit where the ball is out of sight of a user. Asnoted previously, the visibility of the ball may indicate the presenceof a differential pressure greater than a threshold pressure. In thestate shown in FIG. 2, and device 100 located with pivot arm 110 in afirst space, a positive differential pressure in the first space maymove the ball 200 toward the internal stops 124 when the pressureexceeds a threshold based at least partly on the inclination of thepivot arm end. In this case, the non-visibility of the ball 200 wouldindicate an effective positive pressure in the first space, andaccordingly an effective negative pressure in the second space.Alternatively, the ball may be used to indicate a negative pressure inthe first space if the pivot arm is located in the first space and thepivot arm is rotated so that the pivot arm end is inclined at a positiveangle relative to a horizontal plane. In such a case, the visibility ofthe ball positioned against the end stop 118 would indicate a negativedifferential pressure in the first space greater than a thresholddifferential pressure relative to the second space. According to theembodiment of FIGS. 1-2, the pivot arm 110 may pivot ±90° (i.e., 180°)to adjust the threshold air pressure differential monitoringcalibration.

As shown in FIG. 2, the base plate 102 may be configured to receive aplurality of fasteners 103 which may be used to secure the base plate toa barrier. The fasteners employed may be screws, nails, adhesives and/orany other suitable fastener, as the present disclosure is not solimited.

FIG. 3 is a cross-sectional side schematic view of the device 100 ofFIG. 1 showing a continuous fluid channel 126 formed through both sides10, 12 of the barrier and the pivot arm 110. As noted previously, thedevice wall conduit 108 fluidly connects a first space to a secondspace, such that air pressure may be transmitted and measured betweenthe first space and the second space via the device 100. As shown inFIG. 3, a transition region 128 exists where the wall conduit 108 isfirst surrounded by the pivot arm 110 when traveling in a directiontoward the pivot arm. In some embodiments, the transition region iswhere a cylindrical recess surrounds a cylindrical insert. In theembodiment shown in FIG. 3, the wall conduit 108 may extend slightlyinto a cylindrical recess (not shown) in pivot arm 110 where the outersurface of wall conduit 108 engages with an inner surface of thecylindrical recess. This engagement region would be the transitionregion in such an embodiment. In some cases, such as in the embodimentof FIG. 3, the pivot arm is arranged such that pivoting the pivot armwithin a vertical plane (i.e., rotating the pivot arm about a horizontalaxis) does not change a location of the transition region relative tothe first conduit. In some embodiments, such as the embodiment of FIG.3, pivoting the pivot arm does not alter the flow passageway from theconduit to the pivoting arm. For example, the general path that fluidflow would follow to arrive at the pivot arm would not be altered whenthe pivot arm is pivoted. In this manner, significant changes to airflow resistance in the passageway may be limited, yielding a moreaccurate reading device.

FIG. 4 is a front schematic view of another embodiment of a device 100for indicating a directional differential pressure. The embodiment ofFIG. 4 is similar to that of FIGS. 1-2, except that the embodiment ofFIG. 4 is configured to indicate a threshold differential pressurethreshold set point based on the angle of inclination of the pivot armrelative to a horizontal plane. That is, in the depicted embodiment, thepivot arm 110 includes a rotatable base plate 140 which rotatesconcurrently with the pivot arm. The rotatable base plate includes anarrow 144 which is aligned with an end of the pivot arm which isinclined as the pivot arm rotates. Pluralities of markings are disposedon a base plate 102 which is fixed to the wall. The markings aredisposed around a circumference of the rotatable base in a predeterminedinterval and denote various angles of the pivot arm. The markings maycorrespond to threshold differential pressure values from a separatechart or may list threshold differential pressure values. Thus, duringinstallation of the device, the pivot arm may be rotated to a positionso that an appropriate differential pressure threshold may be set for agiven space. As discussed previously, the accuracy of the markings 142may be based on the alignment of the pivot arm axis of rotational with ahorizontal plane, which may be indicated with a first level 120.Additionally, the accuracy may also be partly determined by the rollorientation of the rotatable base 102, the correct orientation of whichis indicated by a second level 122.

FIG. 5 is a front schematic of another embodiment of a device 100 forindicating a directional differential pressure. The device of FIG. 5 issimilar to that of FIGS. 1-2, and includes a pivot arm 110 configured torotate about an axis transverse (e.g., perpendicular) to a barrier onwhich a base plate 102 is secured. A rotatable base 140 is secured tothe pivot arm 110 and is configured to rotate concurrently with thepivot arm. A movable element 200 moves inside the pivot arm between endstop 118 and internal stops 124 depending on the presence of adifferential pressure between two spaces or lack thereof. In contrast tothe embodiments of FIGS. 1-2, the pivot arm includes a differentialpressure set point indicator 150. According to the embodiment of FIG. 5,the differential pressure set point indicator is configured to indicatewhen the pivot arm 110 is inclined at a suitable inclination tocorrespond to a particular differential pressure threshold. That is, thedifferential pressure set point indicator includes a bubble level whichdenotes alignment of the pivot arm at a particular inclination anddifferential pressure threshold. The differential pressure set pointindicator may be used to indicate either a positive or negative pressurethreshold, depending on the orientation of the differential pressure setpoint indicator on the pivot arm. In some embodiments, the differentialpressure set point indicator may be integrally formed with the pivotarm, while in other embodiments the differential pressure set pointindicator may be replaceable or swappable to allow a user to choose fromamong a set of differential pressure thresholds.

The embodiments described below with reference to FIGS. 6-10 aredifferential pressure set point indicators which may be used withdevices of exemplary embodiments described herein. That is, thedifferential pressure set point indicators may be used with any conduit(such as a pivot arm) which contains a movable element that isresponsive to a differential pressure between two spaces. Differentialpressure set point indicators may be used alone or in combination withother indicators, as the present disclosure is not so limited.Additionally, differential pressure set point indicators may beintegrally formed with device of exemplary embodiments described herein,or may be attached separately in a permanent, semi-permanent, orreleasable manner, as the present disclosure is not so limited.

FIG. 6 is a partial cross-sectional view of one embodiment of adifferential pressure set point indicator 150 which is attached to afirst conduit (e.g., a pivot arm) 110 and indicated the a thresholddifferential pressure which moves a movable element (e.g., a ball) 200in the first conduit. Like other bubble differential pressure set pointindicators, this differential pressure set point indicator 150 includesa vial 160 with a liquid and associated bubble pointer 162. The vial maybe appropriately rotated about a pivot 180 with a fastener (e.g., wingnut), capable of loosening and securing rotation of the vial about thepivot so that the vial points to markings 170 that indicatecorresponding threshold differential pressure values that may be setbetween separate spaces which, in turn, correspond to the appropriateangle of inclination of the differential pressure set point indicator150 and, hence, the angle of the conduit 110 itself when the bubblepointer 162 is between the boundary lines 163. For instance, when it isdesired for the device to be installed so as to extend through a walland between separated spaces to indicate to an observer that adirectional differential pressure of at least 0.02 inches of H₂O ispresent, then, in the embodiment of FIG. 6, the angular position of thevial on the pivot 180 is adjusted so that the vial 160 points to theparticular marking that references a pressure of 0.02 inches of H₂O inthe desired direction of potential air flow. Since the differentialpressure set point indicator can sense both directions of the conduitincline, there may be similar symmetric markings for the desiredthreshold differential pressure set point in each direction.Accordingly, the device is appropriately installed such that the pointerof the vial 160 aligns with the appropriate directional differentialpressure markings resulting in the conduit having an angle ofinclination that allows the bubble pointer 162 to remain steady at themiddle of the vial between the boundary lines 163. Hence, afterappropriate installation, a directional differential pressure in thedirection from a first space to a second space of 0.02 inches of H₂O orgreater will generate enough pressure differential and potential airflow forces on the movable element 200 to cause the ball to move from alower end to a higher end.

If it is further desired that the device provide indication to anobserver of whether a particular directional different differentialpressure between spaces is present, then the pivot can be appropriatelyadjusted so that the vial points to the appropriate one of the twosimilar markings which correspond to the desired pressure, of which theappropriate mark of the two is determined by adjusting the conduitincline with the low end in the desired higher pressure space and thehigh end in the desired lower pressure space so that the bubble 162reaches an equilibrium state in the middle of the vial e.g., betweenboundary lines 163. For example, a change in the desired pressuredifference between the spaces from 0.02 inches of H₂O to 0.03 inches ofH₂O with the same desired direction of potential air flow may involve asimple adjustment of the wing nut so that the vial 160 points to thecloser marking that references 0.03 inches of H₂O, which would involvepositioning the conduit at a steeper inclination angle (e.g., byrotating a pivot arm about an axis traverse to a barrier) to put thebubble 162 in between the boundary lines 163. Once the differentialpressure set point indicator is appropriately adjusted and the angle ofinclination of the conduit is set within the wall such that the bubblepointer 162 remains steady at the middle of the vial, the device isready to provide an accurate indication of whether the desired directionof potential air flow and directional threshold differential pressurebetween spaces is actually present.

FIG. 7 is a partial cross-sectional view of another embodiment of adifferential pressure set point indicator 150 attached to a conduit 110via an appropriate base plate 164. The differential pressure set pointindicator includes a vial 160 that contains liquid and an associatedbubble pointer 162. Due to the geometry of the vial and gravity actingon the liquid within the vial, the bubble moves to the highest possiblepoint within the vial. Here, the vial 160 exhibits a geometry (e.g.,curvature) that allows for the bubble to provide differential pressureset point information at multiple regions along the vial. For instance,when the conduit is perfectly level, the bubble moves toward a positionwhere the vial and base plate correlate to being level. However, whenthe conduit is inclined at an angle, the position of the bubble relativeto the vial will change so as to provide an indication that the conduitis set at a different angle of incline.

As shown in FIG. 7, markings 170 are provided adjacent to the vial sothat appropriate differential pressure set point information is providedto an observer (e.g., someone who is adjusting the tilt of the conduit)when the conduit is angled in a manner that brings the bubble intosteady alignment near particular marking(s). Because the differentialpressure set point indicator can sense both directions of the conduitincline (i.e., positive or negative incline relative to a horizontalplane), there are two similar symmetric markings for each desiredthreshold differential pressure set point. Here, the markings 170 referto the threshold directional differential pressure between spacesrequired to generate enough differential pressure and potential air flowforces to move the ball from a lower end of the conduit 110 to a higherend. That is, the conduit 110 may be tilted so that the bubble pointer162 aligns with the appropriate one of the two similar markings whichcorresponds to the desired pressure. The appropriate marking of the twois determined by adjusting the conduit incline with the low end in thedesired higher pressure space or a high end in the desired lowerpressure space so that the bubble 162 remains in steady alignment andpoints to the desired marking that indicates a particular value of thedirectional pressure differential. When the conduit is installed at theangle that corresponds to that particular value of pressuredifferential, movement of the ball 200 to a higher region of the conduitindicates that the directional differential pressure indicated by thebubble 162 exists (or is exceeded) between the separate spaces.

FIG. 8 is a partial cross-sectional view of another embodiment of adifferential pressure set point indicator 150 which includes a weightedball-type differential pressure set point indicator. The differentialpressure set point indicator 150 includes a vial 160 with a weightedball pointer 162. The vial 160 is filled with a fluid (e.g., gas,liquid) and the ball pointer moves to the lowest point within the vialby force of gravity (i.e., weight). The vial 160 may exhibit a curvaturethat permits the ball to provide information regarding the angle ofincline of a conduit 110 when the ball 162 remains in steady alignmentat various regions along the vial. For instance, when the conduit isperfectly level, the ball pointer 162 moves toward the middle of thevial. Though, when the conduit is tilted at an angle, the ball pointer162 may still remain in steady alignment with a region of the vial thatis offset from the middle of the vial.

As shown in FIG. 8, markings 170 are provided adjacent to the vial 160so that appropriate information can be provided when the conduit istilted such that the ball pointer 162 aligns with a particular one ofthe markings. The markings 170 refer to the threshold directionaldifferential pressure set point between spaces required to create asufficient degree differential pressure and potential air flow forcesthat moves the ball 200 within the passageway of the conduit 110 from alower end of the conduit to a higher end. That is, the conduit 110 maybe inclined so that the ball pointer 162 aligns with markings thatindicate a particular value of directional pressure differential. Whenthe conduit is installed at the angle that corresponds to thatparticular value of directional pressure differential, movement of theball 200 within the passageway from the lower end of the conduit 110 tothe higher end of the conduit indicates that the directionaldifferential pressure indicated by the ball pointer 162 actually exists(or is exceeded) between the spaces. Based on how the vial of aball-type differential pressure set point indicator is shaped, themarkings 170 which relate the angle of incline of the conduit to thethreshold pressure differential between spaces are calibrated andappropriately positioned.

The ball-type differential pressure set point indicator of FIG. 8provides for different threshold differential pressure set points.Because the differential pressure set point indicator can sense bothdirections of the conduit incline, there are two similar symmetricmarkings for each desired threshold differential pressure set point. Ofcourse, in other embodiments, a ball-type differential pressure setpoint indicator may provide for threshold differential pressureinformation for inclination of the conduit in only one direction, and sothe markings may be unidirectional. In such an arrangement, theball-type differential pressure set point indicator may provide a finerdegree of set point adjustment markings for indicating whether thethreshold differential pressure between spaces is present.

FIG. 9 is a partial cross-sectional view of another embodiment of adifferential pressure set point indicator 150 having a weighted pointer160. As shown in FIG. 9, the differential pressure set point indicator150 is rigidly secured to the outer surface of a conduit 110 via a baseplate 164. The differential pressure set point indicator 150 includes atip pointer 162 that is pivotally connected to the base plate 164. Aweight 168 is provided at an end opposite the tip pointer below thepivot point 166. When the conduit 110 is placed within a wall at anangle of inclination with respect to a horizontal plane, the tip pointer162 will vary in its position and pivot to reflect the degree to whichthe conduit is tilted with respect to the horizontal.

According to the embodiment shown in FIG. 9, the tip pointer 162 isfurther adapted to rotate about the pivot point 166 so as to point tothe bi-directional reference markings 170 which are calibrated to matchthe angle of incline with the threshold differential pressure betweenopposite ends of the conduit 110 at which the ball 200 will be urgedagainst the force of gravity. As such, depending on the angle of inclineof the conduit, the tip pointer 162 will come into alignment withreference markings 170 that are calibrated to represent minimumdifferential pressures required to move and maintain the ball 200 at adesired position within the conduit, for instance, at the highest point.

FIG. 10 is a partial cross-sectional view of another embodiment of adifferential pressure set point indicator 150 configured as a pendulumdirectional differential pressure set point indicator. The differentialpressure set point indicator 150 is rigidly secured to an outer surfaceof a conduit 110 via a base plate 164. The differential pressure setpoint indicator 150 includes a pendulum pointer 162 that is pivotallyconnected to the base plate 164 at a point 166. Here, the pendulumpointer 162 extends downwardly and rotates about the pivot point 166 soas to point to the bi-directional reference markings 170 which arecalibrated similarly to that described above regarding FIG. 9.

Thus, given a desired minimum differential pressure between enclosedspaces that are separated by a barrier through which a conduit extends,appropriately calibrated differential pressure set point indicators likethose discussed with reference to FIGS. 6-10 may allow the angle ofinclination of the conduit to be easily adjusted to suit the desireddirectional pressure differential. That is, the conduit of a deviceinstalled into a wall separating two enclosed spaces may be oriented ata particular angle that corresponds to a threshold differential pressureset point between the separate spaces sufficient to cause a ball, orother movable element, disposed within the conduit to move from thelower end to the higher end of the conduit. When it is desired for thatthreshold differential pressure between the separate enclosed spaces tobe altered, the differential pressure set point indicator, withappropriately calibrated reference markings, may be used as an easyreference to determine what the adjusted angle of the conduit should beto correspond to the new differential threshold pressure.

FIG. 11 is a front schematic of another embodiment of a device 100 forindicating a directional differential pressure. According to theembodiment shown in FIG. 11, the device includes a base plate 102 whichmay be secured to a barrier with a plurality of fasteners 103. A pivotarm (e.g., a conduit) 110 and a rotatable base 140 are togetherrotatably secured to the base plate so that the pivot arm and rotatablebase may be rotated together about an axis transverse (e.g.,perpendicular) to the barrier on which the base plate is secured. Thepivot arm includes a movable element (e.g., a ball) 200 which isconfigured to move between end stop 118 and internal stops 124 based ona force balance between gravity and any differential pressure betweenspaces fluidly connected though the pivot arm to indicate the presenceof a differential pressure or lack thereof. As discussed previously, thedevice 100 also includes a first level 120 to indicate alignment of therotational axis of the pivot arm and rotatable base with a horizontalplane, whereas the second level 122 indicates alignment of the baseplate 102 in particular roll orientation relative to the same rotationalaxis.

As shown in FIG. 11, the device 100 includes a vial 141 disposed on therotatable base 140. Disposed in the vial is a fluid (e.g., liquid), anair bubble 146, and a weighted ball 148. A plurality of markings 142 arealso disposed on the rotatable base and accordingly rotate when therotatable base is rotated. The markings are disposed at intervals andcorrespond to particular angles of inclination of the pivot arm 110. Theair bubble and weighted ball move as the pivot arm and rotatable baseare rotated to indicate the current differential threshold pressure setpoint corresponding to the angle of inclination relative to a horizontalplane. In contrast to prior embodiments, as the vial 141 and markings142 are both disposed on the rotatable base 140 and are rotatable, theindication of the threshold differential pressure is accurate regardlessof the roll orientation of the base plate. That is, in contrast tostationary markings formed on the base plate 102 or another structurefixed to a barrier, the markings are linked to the position of the pivotarm 110. Accordingly, in the embodiment of FIG. 11, the base plate doesnot need to be aligned in a roll orientation relative to a rotationalaxis of the pivot arm using second level 122 to provide accuratedifferential pressure threshold readings. Thus, the embodiment of FIG.11 greatly simplifies installation and accurate threshold pressuresetting. According to the embodiment of FIG. 11, the marks indicatepressure values, or may correspond to lookup values in separate chart.

In some cases, the first level 120 may be arranged as a curved tubewhere the curve is disposed in a single plane. In such an arrangement,the first level 120 may provide accurate readings when the first levelis correctly oriented and aligned in a vertical plane, or another planefor which the curve is calibrated, but may provide inaccurate ordistorted readings when the first level is not in the vertical orcalibrated plane. Thus, when the first level is arranged with a vialhaving a single curve which is not agnostic to a roll orientation of thefirst level relative to a horizontal axis, it may be desirable for auser to receive indication as to the accuracy of the first level, sothat the alignment of axis of rotation of the rotatable base 140 with ahorizontal plane may be discovered accurately. Accordingly, second level122 may be used to determine whether the first level 120 is correctlyoriented or aligned in a vertical plane (or another plane ofcalibration) so that the user can confirm that the first level isproviding an accurate reading. The second level may be a barrel viallevel which itself is agnostic to a roll orientation of the second leveland may therefore provide an accurate reading as to the alignment of thefirst level with a vertical plane. In some embodiments, the air bubble146 and/or weighted ball 148 may be used to indicate whether the firstlevel 120 is aligned in a vertical plane. For example, alignment of theair bubble and/or weighted ball with the first level 120 may indicatethat the first level is in a vertical plane. In one embodiment, a lineor other marking disposed on the wall plate 102 may assist a user inchecking the alignment of the air bubble and/or weighted ball with thefirst level. Of course, any suitable arrangement of levels or vials maybe employed to indicate whether the first level 120 is providing anaccurate measurement or reading, as the present disclosure is not solimited.

In some cases, the second level may be arranged as a curved tube levelwhere the curve is disposed in a single plane. In such an arrangement,the second level 122 may provide accurate readings when the second levelis correctly oriented and aligned in a vertical plane, or another planefor which the curve is calibrated, but may provide inaccurate ordistorted readings when the second level is not in the vertical orcalibrated plane. Thus, when the second level is arranged with a vialhaving a single curve which is not agnostic to a roll orientation of thesecond level relative to a horizontal axis, it may be desirable for auser to receive indication as to the accuracy of the second level, sothat the correct roll orientation of the wall plate 102 may bedetermined. Accordingly, first level 120 may be used to determinewhether the first level 120 is correctly oriented or aligned in avertical plane (or another plane of calibration) so that the user canconfirm that the first level is providing an accurate reading. The firstlevel may be a barrel vial level which itself is agnostic to a rollorientation of the first level and may therefore provide an accuratereading as to the alignment of the second level in a vertical plane. Ofcourse, any suitable number and type of levels (including curved tubelevels and barrel vial levels) may be employed to verify the accuracy ofother levels employed in a device or differential pressure set pointindicator, as the present disclosure is not so limited.

FIG. 12 is a front view of another embodiment of a differential pressureset point indicator 250 configured to provide an accurate differentialpressure set point indication regardless of movement of a conduit 110outside of a vertical plane. As noted previously, the accuracy ofinclinometers and other threshold indicating devices may be dependent onthe alignment of the inclinometer with a vertical plane. That is, aninclinometer attached to a conduit which moves in a non-vertical planemay need special calibration or may otherwise report inaccurate valuesas the conduit is moved. For example, if a conduit is moved in a rolldirection so that an attached differential pressure set point indicatoris also moved in roll as the conduit is moved, the effect of gravity onan air bubble, weighted ball, pointer, etc. may cause the reporteddifferential pressure to be inaccurate. The indicator of FIG. 12addresses the susceptibility of the indicator to movement outside of avertical plane by allowing the indicator itself to rotate about theconduit 110 to align the indicator with an indication plane (e.g., avertical plane).

As shown in FIG. 12, the differential pressure set point indicator 250includes a support 252 which is secured to the conduit 110 whichcontains a movable element 200. In particular, the conduit has beenplaced inside the support through an opening 254. According to thisembodiment, the support is flexible so that the support may be coupledto the conduit in a direction transverse to a longitudinal axis of theconduit. In this and other embodiments, the support may also be attachedto the conduit in a direction parallel to the conduit's longitudinalaxis (e.g., by fitting the support over an end of the conduit). Ofcourse, in other embodiments the support may be rigid and/or maycompletely surround the conduit, as the present disclosure is not solimited. The support 252 allows for rotation of the indicator about thelongitudinal axis of the conduit (i.e., in a roll direction). In theembodiment of FIG. 12, the support and conduit may be a suitably lowcoefficient of friction to allow the support to be rotated on theconduit either under force from a user or under passive urging (e.g.,with weight). In other embodiments, the support may include a bushing orbearing coupling the support to the conduit to reduce the friction ofthe support as it rotates about the conduit.

According to the embodiment in FIG. 12, the support includes ahorizontal face 256 and a vertical indication face 258. A vial 260 isdisposed on the vertical indication face which includes a weighted balland an air bubble which are used to indicate the differential pressurethreshold corresponding to an angle of inclination of the conduit. Inparticular, the vial is used to indication an angle of inclination ofthe horizontal face 256 relative to a horizontal plane. As shown in FIG.12, the horizontal face 256 includes a level 270 including a bubble 272which indicates alignment of the horizontal face 256 with a horizontalplane. In some embodiments, the level may be a barrel vial level whichaccurately indicates alignment with the horizontal plane if the level270 is not in a horizontal plane. As noted previously, the horizontalface may be inclined relative to the horizontal plane. Accordingly, thelevel 270 indicates alignment of the horizontal face with a horizontalplane when the conduit is level. The level 270 also indicates when theindication face is aligned with a vertical plane (i.e., an indicationplane). Thus, regardless of the inclination and position of the conduit110, the support may be rotated about the conduit until the indicationface is aligned with an indication plane, as indicated by the level. Inthe depicted embodiment, the indication plane is a vertical plane,although other indication planes may be employed, as the presentdisclosure is not so limited.

FIG. 13 is a side view of the differential pressure set point indicator250 of FIG. 12 clearly showing the indication face 258 including vial260. As shown in FIG. 13, the vial includes an air bubble 264 and aweighted ball 266 which move to different portions of the vial under theeffect of gravity (i.e., weight) as the conduit 110 is inclined relativeto a horizontal plane. A plurality of markings 262 are disposed inintervals around the vial and denote various pressure values orcorrespond to lookup pressure values in a separate chart. As notedpreviously, regardless of the orientation and position of the conduit,the support 252 may be rotated about the longitudinal axis of theconduit until the level 270 indicates the indication face 258 is alignedwith an indication plane (e.g., a vertical plane) so that the valuesreported by the markings 262 are accurate.

As shown in FIG. 13, in some embodiments the differential pressure setpoint indicator 250 also includes a set screw 268 which may be used tosecure the support 252 to the conduit 110 so that the differentialpressure set point indicator is not rotatable about the conduit. Such anarrangement may be desirable when the conduit and differential set pointindicator are positioned in correct positions, so that inadvertentcontact (e.g., bumping) does not move the differential set pointindicator 250 out of alignment with the indication plane. In otherembodiments, a spring loaded detent may engage a depression orreceptacle formed on the conduit to resist rotation of the differentialpressure set point indicator about the conduit. In still otherembodiments, the support 252 may include a clamp which reduces thediameter of the support to increase friction between the support and theconduit to rotatably secure the differential pressure set pointindicator to the conduit. Of course, any suitable rotation stop may beemployed to selectively inhibit rotation of the support 252 about theconduit, as the present disclosure is not so limited.

According to the embodiment depicted in FIG. 13, the differentialpressure set point indicator 250 includes an end stop connector 253which couples rotation of the end stop 118 to the rotation of thesupport 252 about the conduit 110. That is, when the differentialpressure set point indicator is rotated about the conduit the end stopis also rotated about the conduit. As will be discussed further withreference to FIG. 14, the end stop may have an off-center orifice 119relative to the conduit for receiving the movable ball 200, and thisrotation may ensure the axis of the orifice is aligned with a center ofthe ball. Alternatively or in combination to the end stop connector, theend stop 118 may include ramps configured to align the center of theball 200 with the center of the orifice when the ball abuts the end stopor internal stop.

According to the embodiment of FIG. 14, the differential pressure setpoint indicator 250 may also be coupled to an internal stop 124 disposedin the conduit via an internal stop connector 255. Similarly to the endstop connector 253 and end stop 118, rotation of the differentialpressure set point indicator 250 may rotate the internal stop so that anorifice 125 formed in the internal stop aligns with a center of the ball200. The alignment of the orifice of the internal stop may be indicatedto a user via a bubble level indicating a predetermined roll position,or with markings disposed around a circumference of the conduit. As thedifferential pressure set point indicator 250 may rotate automatically(i.e., under urging from weight), the orifice of the internal stop maybe aligned with the center of the ball automatically. In someembodiments, the internal stop may include a centered orifice and a rampon which a movable element (e.g., a ball) may ride up on in response toa differential pressure. The ramp may be formed around a circumferenceof the orifice and sized and shapes to ensure alignment of a center ofthe ball with the orifice when the ball abuts the internal stop. Forexample, the ramp may be frustoconical in some embodiments. Thus, thedifferential pressure set point indicator 250 may automatically ormanually align the centerline of an orifice formed in an end stop andinternal stop to limit fluid (e.g., air) flow through a conduit. In someembodiments, the internal stop may be a unitary component such as a diskwith an orifice formed therein. In other embodiments, the internal stopmay be configured as one or more posts or walls which restrict movementof the ball 200 in the conduit 110.

FIG. 14 is a side view of another embodiment of a differential pressureset point indicator 250 showing the functionality of the end stopconnector 253. As shown in FIG. 14, and noted previously, the end stop118 includes an orifice which is off-center relative to a longitudinalaxis of the conduit 110. That is, the conduit has a central longitudinalaxis A-A about which the indicator 250 and end stop 118 rotate. However,the orifice is centered on axis B-B which is offset from thelongitudinal axis of the conduit. The axis B-B is aligned with a centerof movable ball 200 which is sized and shaped to roll inside the conduit110 and accordingly has a center which is disposed below thelongitudinal axis of the conduit. If the conduit is moved and undergoesa change in roll orientation (i.e., rotation about its longitudinal axisA-A), the ball 200 will move toward the lowest point under the effect ofgravity (i.e., weight) so that the center of the ball and the centralaxis B-B of the orifice are no longer aligned. As a result, when theball abuts the end stop 118, the ball may not form an effective airbarrier with the orifice as would be the case if the central axis of theorifice and the center of the ball were aligned. According to theembodiment of FIG. 14, the end stop connector 253 allows the end stop118 and orifice central axis B-B to be adjusted to match the center ofthe ball 200. That is, when the indicator 250 is rotated about thelongitudinal axis to align the indication face 258 with an indicationplane (e.g., vertical plane), the orifice central axis will also bemoved into alignment with the center of the ball 200, so that an airbarrier may be formed when the ball is received in the orifice. Ofcourse, in other embodiments the end stop may be separately adjustableor otherwise not linked to the differential pressure set point indicator250, as the present disclosure is not so limited.

As shown in FIG. 14, the internal stop 124 includes ramps 257 which areformed around the circumference of the conduit 110. When the ball 200 isurged by gravity (i.e., weight) or a differential pressure, the ballwill ride up on the ramp 257 so that the center axis B-B of the ball 200is aligned with the center axis A-A of the internal stop orifice 125.Accordingly, the internal stop may remain stationary relative to theconduit 110 and will still ensure the movable element 200 forms a fluidbarrier with the internal stop when the movable element abuts theinternal stop. In some embodiments, such an arrangement may also beemployed with regards to the end stop 118 so that the end stop connector253 is omitted. Of course, any suitable combination of ramps androtatable offset orifices may be employed with a differential set pointindicator, as the present disclosure is not so limited.

As shown in FIG. 14, alternative forms of the vial 260 may be employedto indicate the differential pressure set point. The vial 260 of FIG. 14is split into two separate vials, with one vial containing the airbubble 264 and the other vial containing the weighted ball 266. Ofcourse, any suitable indicator may be employed, as the presentdisclosure is not so limited.

In some embodiments, an end stop that forms a suitable fit (e.g.,interference fit, snap fit) over an end of a conduit may include a soundattenuator. In some cases, a movable element may be a plastic ball(e.g., a ping pong ball) and the end stop may be made of a hard plastic.Thus, without inclusion of the sound attenuator between the conduit andthe end stop, when the ball impacts against the end stop, an abruptsound may be produced which can be easily heard by a person located inthe space where the impact occurs, and possibly in an adjacent spacewhere the other open end of the conduit resides. When the soundattenuator is placed between the conduit and the end stop, impact of theball against the sound attenuator will produce a much softer sound whichis not as readily noticeable as compared with the sound produced whenthe energy-absorbing material is not present. The sound attenuator maybe formed in a separate layer on the end stop, or may be integrated intothe end stop (e.g., the end stop may exhibit a geometry similar to adiaphragm), as the present disclosure is not so limited.

In some embodiments, there may not be an alignment of the travel path ofthe center of the ball and an opening at the end of the conduit. Forexample, an interior-facing portion of an opening at the end of theconduit may be arranged and positioned such that the movable elementsubstantially prevents air flow when the movable element abuts theinterior-facing portion of the opening, yet a center axis of the opening(e.g., the centroid of the area of the opening) is not aligned with atravel path of a center of the movable element. A ramp may be presenttoward the end of the conduit such that the movable element is pushed upinto the opening.

FIG. 15 is a front view of the differential pressure set point indicator250 of FIG. 12 in a first position where the indication face 258 is outof alignment with an indication plane, which in this case is a verticalplane. The position shown in FIG. 15 may be produced by movement of theconduit 110 outside of a single vertical plane, which may induce roll ofthe conduit which would move the indication face out of alignment withthe indication plane. The level 270 indicates that the indication face258 is out of alignment with the indication plane as the air bubble 272is not centered in the level. Likewise, the level also indicates thehorizontal face 256 is out of alignment with a horizontal plane.Accordingly, a user of the differential pressure set point indicatorwould be aware that the values reported via the vial 260 disposed on theindication face 258 may be inaccurate and that the differential pressureset point indication should be adjusted. As shown in FIG. 15, thedifferential pressure set point indicator may include a weight 280 whichurges the indicator to rotate about the conduit 110, as shown by thearrows. The coefficient of friction between the support 252 and theconduit 110 may be suitably low so that the weight 280 moves theindication face 258 into alignment with the indication plane without anymanual adjustment from a user. Accordingly, a user may verify thealignment of the indication face with the indication plane with thelevel 270, but will generally need to take no action to manually adjustthe indicator when the conduit is moved in a roll direction.

FIG. 16 is a front view of the differential pressure set point indicatorof FIG. 15 in a second position. The second position shows thedifferential pressure set point indicator properly aligned with theconduit to accurately report pressure threshold values with the vial260. That is, the indication face 258 is aligned with an indicationplane (i.e., a vertical plane) so that markings disposed on theindication face and any weighted balls or air bubbles in the vial areproperly calibrated. The level 270 verifies the correct alignment of theindicator 250, as the air bubble 272 is disposed in the center of thevial. In the position shown in FIG. 16, the center of gravity of theindicator 250 may be aligned with the center of the conduit 110 so thatthere is no moment on the indicator urging the support to rotate aboutthe conduit.

FIG. 17 is a side cross-sectional schematic of another embodiment of adevice 300 for indicating a directional differential pressure whichallows a second pivot arm (i.e., second conduit) 330 to be positionedanywhere within a semi-spherical range of motion. The device includes abase plate 302 which is fixed to a first side 10 of a barrier. The baseplate includes a receptacle which receives a flanged end 312 of a firstpivot arm (i.e., first conduit) 310 in a similar manner to theembodiment of FIGS. 1-2. The base plate also includes a groove 306 whichreceives guides 314 of the first pivot arm which constraint the firstpivot arm to rotated about a single axis transverse to the barrier 10,12. In the depicted embodiment, the first pivot arm rotates about axisC-C which is perpendicular to the barrier. The device also includes awall conduit 308 which fluidly connects a second space on the secondside 12 of the barrier to the first pivot arm. Like the embodiment ofFIGS. 1-2, the base plate may also include a first level 320 whichindicates alignment of the first pivot arm axis C-C with a horizontalplane, and a second level 322 which indicates a roll orientation of thebase plate.

As shown in FIG. 17, the device 300 also includes a second pivot arm 330which is rotatably coupled to the first pivot arm 310. The second pivotarm is configured to rotate about a second pivot arm axis D-D which istransverse to the first pivot arm axis C-C. For example, in the depictedembodiment, the second pivot arm axis is perpendicular to the firstpivot arm axis. The second pivot arm contains a movable element (e.g., aball) 200, which is contained in the second pivot arm with end stop 318and internal stops 324. The second pivot arm also includes a transparentwindow 316 which allows a user to view the movable element in certainstates of the device to indicate a presence or lack of a thresholddifferential pressure between a first space on the first side 10 of thebarrier and the second space on the second side 12 of the barrier. Anoptional shield 332 protects the end stop 318 disposed on the secondpivot arm.

As the second pivot arm has two effective axes of rotation (i.e., axisC-C and axis D-D), the second pivot arm may be oriented in any desirabledirection within a semi-spherical range of motion regardless of aninclination of the barrier 10, 12. That is, the first pivot arm isrotatable 360° about the first pivot arm axis C-C (i.e., in a rolldirection), while the second pivot arm is rotatable at least 180° aboutthe second pivot arm axis D-D (i.e., in a pitch or yaw direction).Accordingly, the second pivot arm may be oriented in any suitabledirection within a semi-sphere defined by a combination of the range ofmotion about each axis individually. Accordingly, any desirablethreshold pressure for indication may be achieved by adjusting one ormore of the pivot arms about their respective axes. As the first pivotarm is rotatably mounted close to flush with the first side 10 of thebarrier, the distance the first and second pivot arms extend from thewall may be reduced. In some orientations, the second pivot arm mayextend no further from the wall in a direction perpendicular to the wallthan a single pivot arm device, meaning the device of FIG. 17 may beeasily employed in areas where space is limited.

According to the embodiment of FIG. 17, the device forms a channel 326which has a continuous shape and size regardless of the orientation ofthe first pivot arm 310 or second pivot arm 330. As shown in FIG. 17,the channel begins on one side with wall conduit 308 which fluidlyconnects to the second space on the second side 12 of the barrier. Thechannel then transitions to the first pivot arm at first transition 328.The first transition is circular, and does not change in cross-sectionor otherwise alter flow of air when the first pivot arm is rotated aboutthe first pivot arm axis. The channel then continues through the firstpivot arm to a second transition 329 between the first pivot arm and thesecond pivot arm. Similarly to the first transition, the secondtransition is also circular and has no change in cross section when thesecond pivot arm is rotated relative to the first pivot arm.Accordingly, there is no change in air flow path when the second pivotarm is rotated which may otherwise affect the pressure in the secondpivot arm. The channel then continues and culminates on the other end atorifice 319 which is formed in the end stop 318. Thus, the entirechannel has the same overall shape and size with reference to air flowregardless of the orientation of either the first pivot arm or secondpivot arm. Such an arrangement allows for a simpler and more accuratemeans of calibrating the threshold differential pressure set pointmarkings.

While the first pivot arm 310 and second pivot arm 330 of FIG. 17 may berotatable in a range of 360° (i.e., ±180°) and 180° (i.e., ±90°),respectively, the first and second pivot arms may be rotatable in anydesirable range of motion. In some embodiments, the first and/or secondpivot arms may be rotatable by at least ±30°, ±45°, ±60°, ±75°, ±90°,±115°, ±130°, ±150°, ±180°, or any other desirable range about theirrespective axes. In other embodiments, one or both of the first andsecond pivot arms may be pivotable in only one direction. For example,the first and/or second pivot arm may be adjustable between 0° and +90°,0° and −90°, 0° and +60°, 0° and −60°, and/or any other suitablecombination of the above ranges.

In a first space with positive differential air pressure, air may flowin a direction from the first space to the second space. In a space withnegative differential air pressure, air may flow into the first spacefrom the second space (i.e., external environment). Depending on thedirectional differential pressure, the pivot arms may be oriented indifferent directions so that the movable element 200 may indicate thepresence of the correct directional threshold differential pressure.

For a positive pressure first space, the second pivot arm 330 located inthe first space may be pitched downward to correspond to a chosenthreshold differential pressure. Orienting the second pivot arm 330downward increases the force needed to push the ball 200 from thetransparent window 316 and toward the second pivot arm 330. A positivedifferential air pressure may move the ball 200 to a stationary positionin the pivot arm 330 against the internal stops 324. Not viewing thepressure indicator ball may indicate that the first space has theappropriate positive air pressure relative to the second space.Accordingly, the second space has a corresponding negative pressurerelative to the first space. If the pressure indicator is visible withinthe optically transparent portion 316 of the second pivot arm, thedirectional differential air pressure may be incorrect or below thepressure for which the device is calibrated and the user may be alertedto that fact.

For a negative pressure first space, the second pivot arm 330 located inthe first space may be pitched upward to correspond to a chosenthreshold differential pressure. Orienting the pivot arm 330 upwardincreases the force needed to push the ball 200 from the second pivotarm and toward the transparent window 316. A negative differential airpressure in the first space may move the ball to a stationary positionin the transparent window 316 against the end stop 318. Viewing the ballmay indicate that the first space has the appropriate negative airpressure relative to the second space. Accordingly, the second space hasa corresponding positive pressure relative to the first space. If theball is not visible within the transparent window 316, the first spacedifferential air pressure is higher than the pressure for which thedevice is calibrated and the user may be alerted to that fact. Ofcourse, while a ball is shown in FIG. 17, any suitable movable elementor indicator may be employed, as the present disclosure is not solimited.

FIG. 18 is a front schematic of the device 300 of FIG. 17. As shown inFIG. 18, the second pivot arm 330 is oriented in a downward position. Asnoted previously, the first pivot arm 310 rotates about first pivot armaxis C-C which extends in a direction perpendicular to a barrier towhich the base plate 302 is secured with a plurality of fasteners 303.The second pivot arm 330 is rotatably coupled to the first pivot arm viaa second pivot arm linkage 311 which allows the second pivot arm torotate about second pivot arm axis D-D which extends in a directionperpendicular to the first pivot arm axis. Accordingly, the second pivotarm may be oriented in any direction within the range of motion of thefirst pivot arm and second pivot arm, which in some embodiments may be asemi-spherical range of motion.

FIG. 19 is a perspective view of another embodiment of a device 300 forindicating a threshold directional differential pressure in a firstposition. The device of FIG. 19 is similar to that shown in FIGS. 17-18,insofar as the device includes a first pivot arm 310 which rotates abouta first pivot axis C-C transverse to a barrier and a second pivot arm330 which rotates about a second pivot arm axis D-D which is transverseto the first pivot arm axis. The device is secured to a barrier via abase plate 302 via a plurality of fasteners 303. A movable element isdisposed in the second pivot arm and is configured to indicate thepresence or lack of a threshold directional differential pressure. Incontrast to the embodiment of FIGS. 17-18, the device of FIG. 19includes a differential pressure set point indicator 250 which isarranged similarly to the indicator of FIG. 12. That is, the indicatorincludes a support 252 which is rotatable secured to the second pivotarm, so that the indicator may be rotated about a longitudinal axis E-Eof the second pivot arm. The indicator may be rotated about the secondpivot arm to align a vial 260 with an indication plane, which in thedepicted embodiment is a vertical plane. A weighted ball 266 disposed inthe vial may be used to indicate the differential pressure threshold atwhich a movable element disposed in the second pivot arm (see FIG. 20)is visible or invisible as a result of differential pressure. Theindicator also includes a level 270 which indicates correct alignment ofthe vial with the indication plane. As the second pivot arm is orientedin any position, the indicator 250 may be rotated about the longitudinalaxis E-E to align the vial 260 in an indication plane.

In some embodiments, the indicator 250 may be rigidly secured to thesecond pivot arm 330 so that the relative angle of the indicator may notbe changed relative to longitudinal axis E-E. In such an embodiment, thefirst pivot arm 310 and second pivot arm 330 could be adjusted until thelevel 270 indicates the vial 260 is aligned in an indication plane.Accordingly, the arrangement of the pivot arms may allow for a correctindication of threshold pressure even if the differential pressure setpoint indicator 250 is not rotatable relative to the second pivot arm.

As shown in FIG. 19, the device also includes a first pivot arm rotationlock 305 and a second pivot arm rotation lock 313. In the embodiment ofFIG. 19, each of the rotation locks are arranged as screws which may betightened to prevent rotation of either the first pivot arm or secondpivot arm about their respective axes. Such an arrangement is beneficialin permanent or semi-permanent installations where the thresholdpressure may be a constant value and there is no need to adjust thedevice after it is properly oriented and calibrated. Of course, anysuitable arrangement may be employed to selectively restrict therotation of either the first pivot arm or second pivot arm, includingdetents as one example, as the present disclosure is not so limited.

FIG. 20 is a perspective view of the device 300 of FIG. 19 in a secondposition. Relative to the position shown in FIG. 19, the second pivotarm 330 has been rotated about the second pivot arm axis D-Dapproximately 180° which may be the approximate rotational range of thesecond pivot arm. As clearly shown in FIG. 20, a movable element (e.g.,a ball 200) is disposed in the second conduit and is responsive todifferential pressure between two spaces connected by the device andgravity (i.e., weight). A shield 332 protects the movable element. Thelevel 270 is also clearly shown in FIG. 20 disposed on the differentialpressure set point indicator 250 which indicates an alignment of thevial 260 with the indication plane. According to the position shown inFIG. 20, the indicator has been rotated approximately 180° about thelongitudinal axis E-E of the second pivot arm so that the vial 260 isproperly displayed and aligned with an indication plane. An air bubble264 is also shown in FIG. 20 which may be used alone or in combinationwith weighted ball 266 to indicate a differential pressure threshold.

FIG. 21 is a perspective view of the device 300 of FIG. 19 in a thirdposition. Compared with the position of FIG. 20, the first pivot arm 310has been rotated approximately 90° relative to the first arm pivot axisC-C. The second pivot arm 330 has also been rotated approximately 90° sothat the longitudinal axis E-E of the second pivot arm has been alignedwith the first pivot arm axis. Accordingly, in the position of the firstpivot arm 310 shown in FIG. 21, the second pivot arm effectivelyfunctions as a turret-type pivot arm and its rotation about the secondpivot arm axis adjusts the inclination of the second pivot arm relativeto a horizontal plane. The differential pressure indicator 250 has alsobeen rotated approximately 90° so that the vial 260 is aligned with anindication plane.

FIG. 22 is an exploded view of the device 300 of FIG. 19. As shown inFIG. 22, base plate 302 cooperates with a backing ring 342 which isdisposed on an opposite side of a barrier so that fasteners 303 arrangedas screws can secured the base plate to the barrier. The base plate alsosecured a rotational coupling 340 which received the first pivot arm 310and enables rotation of the first pivot arm about the first pivot armaxis. A wall conduit 308 is fluidly coupled through the rotationalcoupling and to the first pivot arm. The first pivot arm 310 includes aspindle 313 which forms a rotational coupling for the second pivot armand a cover plate 315 which forms the air channel through the firstpivot arm when secured. A cover plate 315 may be appropriate when thefirst pivot arm is injection molded. In other embodiments, the firstpivot arm may be unitary and may be formed with any suitablemanufacturing process such as 3D printing, as the present disclosure isnot so limited. The second pivot arm 330 is rotatably mounted on thespindle 313 and includes a transparent conduit 316 which enables themovable element 200 to be seen through the transparent conduit incertain states of the device. The second pivot arm includes internalstop 336 which retains the movable element within the second pivot arm.As shown in FIG. 22, the threshold differential pressure indicator 250includes a support and support O-rings 334. The O-rings may assist inproviding an appropriate air seal between the components of the secondpivot arm. In some embodiments, the O-rings may also increase thecoefficient of friction between the support 252 and the second pivot armso that the differential pressure indicator is rigidly secured to thesecond pivot arm.

FIG. 23 is a cross-sectional view of the device 300 of FIG. 19. As shownin FIG. 23 and similar to the embodiment of FIGS. 17-18, the device ofFIG. 23 forms a fluid (e.g., air) channel with a constant overall shaperegardless of the relative positioning of either the first pivot arm andsecond pivot arm. That is the cross section of the air channel 326remains unchanged throughout the device when either the first pivot armor second pivot arm are rotated about their respective axes. As shown inFIG. 23, the channel 326 includes a first transition 328 which iscircular and is aligned with a direction of the first pivot arm axis.Accordingly, when the first pivot arm is rotated there is no change tothe first transition 328 which would affect air flow. Likewise, a secondtransition 329 is also circular and aligned with a direction of thesecond pivot arm axis. Accordingly, the second transition also does notchange in a manner which would affect airflow when the second pivot armis rotated. Thus, the device shown in FIG. 23 ensures consistent airflowthrough channel 326 regardless of the orientation of the first pivot arm310 and second pivot arm 330.

It should be noted that while screws are shown in exemplary embodimentsdescribed herein, any suitable arrangement may be employed to joinvarious components such as pivot arms, base plates etc. For example,press-fit, snap together elements, positioning detents, and adhesivesmay be used alone or in combination to replace the screws and supplementthe screws shown herein.

The conduit(s) of exemplary embodiments described herein may include anysuitable material. In some embodiments, the conduit(s) may be made up ofglass, plastic, or another appropriate material. In some cases, theconduit(s) may be transparent or translucent so that the movable elementwithin the conduit is viewable to an observer. In some embodiments, theconduit(s) are rigid, though, in various embodiments, the conduit(s) areflexible. The device may include a combination of rigid and flexibleconduits. A conduit need not be cylindrical in shape as any suitableshape may be used.

In some cases, devices of exemplary embodiments described herein mayinclude a fire stop system that, upon the detection of a threshold levelof smoke or fire, provides a barrier that blocks or otherwise mitigatestravel of the smoke/fire from one space or room to another. The firestop system may include various components used to seal the passagewithin the wall. For example, the fire stop may include an intumescentsubstance that swells significantly as a result of heat exposure. Thefire stop materials may be appropriately installed, for example,employing intumescent material as known to those of ordinary skill inthe art. In some cases, the intumescent substance may produce char,which is a substance that acts to retard heat transfer. Devices ofexemplary embodiments herein may be employed in fire-rated ornon-fire-rated applications, as the present disclosure is not solimited.

While the present teachings have been described in conjunction withvarious embodiments and examples, it is not intended that the presentteachings be limited to such embodiments or examples. On the contrary,the present teachings encompass various alternatives, modifications, andequivalents, as will be appreciated by those of skill in the art.Accordingly, the foregoing description and drawings are by way ofexample only.

What is claimed is:
 1. A device for indicating a presence of adirectional differential pressure between a first space and a secondspace separated from the first space by a barrier, the devicecomprising: a rotatable base configured to be rotatably attached to thebarrier; a first conduit coupled to the rotatable base, wherein when therotatable base is rotated, an inclination of the first conduit isadjusted relative to a horizontal plane; at least one movable elementdisposed within the first conduit and movable from a first, verticallylower region of the first conduit to a second, vertically higher regionof the first conduit in response to the directional differentialpressure between the first space and the second space being greater thana threshold differential pressure; and a differential pressure set pointindicator fixed to the rotatable base, wherein the differential pressureset point indicator includes a vial shaped in an arc and at least onemovable marker disposed in the vial.
 2. The device of claim 1, whereinthe rotatable base rotates about an axis transverse to the barrier. 3.The device of claim 1, wherein the first conduit is movable to aninclination of at least 30° relative to the horizontal plane in apositive or negative direction.
 4. The device of claim 1, wherein thefirst conduit is movable to an inclination of 90° relative to thehorizontal plane in a positive or negative direction.
 5. The device ofclaim 1, wherein the first conduit includes an opaque portion configuredto hide the at least one movable element and a transparent portionconfigured to show the at least one movable element, wherein visibilityof the at least one movable element indicates whether the directionaldifferential pressure between the first space and the second space isgreater than the threshold differential pressure.
 6. The device of claim1, wherein the first conduit includes an internal stop disposed in aportion of the first conduit positioned on a first space side of thebarrier, wherein the internal stop keeps the at least one movableelement on the first space side of the barrier.
 7. The device of claim1, wherein the at least one movable marker includes at least one of agroup of a weighted ball and an air bubble.
 8. The device of claim 1,wherein the first conduit moves within a single plane.
 9. The device ofclaim 1, wherein a first conduit-to-base coupling includes a bend. 10.The device of claim 9, wherein the bend is a 90 degree bend.
 11. Thedevice of claim 1, further comprising a wall plate configured torotatably secure the rotatable base to the barrier, wherein the wallplate comprises a first level configured to indicate whether thedifferential pressure set point indicator is aligned with an indicationplane.
 12. The device of claim 11, wherein the wall plate furthercomprises a second level configured to indicate whether the first levelis correctly oriented relative to a vertical plane.
 13. The device ofclaim 1, further comprising a wall plate configured to rotatably securethe rotatable base to the barrier, wherein the wall plate comprises afirst level configured to indicate whether the wall plate is in acorrect roll orientation.
 14. The device of claim 13, wherein the wallplate further comprises a second level configured to indicate whetherthe first level is correctly oriented relative to a vertical plane. 15.The device of claim 1, wherein the first conduit includes a rotatableend stop configured to retain the at least one movable element in thefirst conduit.
 16. The device of claim 15, wherein the rotatable endstop includes an orifice sized and shaped to receive the at least onemovable element such that a fluid barrier is formed by the at least onemovable element when the at least one movable element abuts the orifice.17. The device of claim 1, wherein the first conduit includes arotatable internal stop configured to retain the at least one movableelement in the first conduit.
 18. The device of claim 17, wherein therotatable internal stop includes an orifice sized and shaped to receivethe at least one movable element such that a fluid barrier is formed bythe at least one movable element when the at least one movable elementabuts the orifice.
 19. A device for indicating a presence of adirectional differential pressure between a first space and a secondspace separated from the first space by a barrier, the devicecomprising: a rotatable base configured to be rotatably attached to thebarrier; a first conduit coupled to the rotatable base, wherein when therotatable base is rotated, an inclination of the first conduit isadjusted relative to a horizontal plane; at least one movable elementdisposed within the first conduit and movable from a first, verticallylower region of the first conduit to a second, vertically higher regionof the first conduit in response to the directional differentialpressure between the first space and the second space being greater thana threshold differential pressure; and a wall plate configured torotatably secure the rotatable base to the barrier, wherein the wallplate comprises: a first level configured to indicate whether an axis ofrotation of the first conduit is aligned with the horizontal plane, anda second level configured to indicate whether the wall plate is in acorrect roll orientation relative to the axis of rotation of the firstconduit.
 20. The device of claim 19, wherein the rotatable base rotatesabout an axis transverse to the barrier.
 21. The device of claim 19,wherein the first conduit moves within a single plane.
 22. The device ofclaim 19, wherein the at least one movable element comprises a singlemovable element.
 23. The device of claim 19, wherein the at least onemovable element comprises a ball.
 24. The device of claim 19, whereinthe first conduit is movable to an inclination of at least 30° relativeto the horizontal plane in a positive or negative direction.
 25. Thedevice of claim 24, wherein the first conduit is movable to aninclination of 90° relative to the horizontal plane in a positive ornegative direction.
 26. The device of claim 19, wherein the first levelis configured to indicate whether the second level is correctly orientedrelative to a vertical plane.
 27. The device of claim 26, wherein thefirst level is a barrel vial bubble level.
 28. The device of claim 19,wherein the second level is configured to indicate whether the firstlevel is correctly oriented relative to a vertical plane.
 29. The deviceof claim 28, wherein the second level is a barrel vial bubble level. 30.The device of claim 19, further comprising a differential pressure setpoint indicator configured to indicate a threshold directionaldifferential pressure between the first space and the second space. 31.The device of claim 30, wherein the differential pressure set pointindicator includes a plurality of markings disposed on the wall plateand a marker disposed on the rotatable base.
 32. The device of claim 30,wherein the differential pressure set point indicator is disposed on thefirst conduit, and the differential pressure set point indicatorincludes a vial shaped in an arc and at least one movable markerdisposed in the vial.